1. Field of the Invention
The present invention relates to a belt conveyor that conveys an image receiving medium held on a conveying belt to a developed image formed on an image carrier, and an image forming apparatus that transfers the developed image onto the image receiving medium conveyed by the belt conveyor and thereby forms an image onto the image receiving medium.
2. Description of the Related Art
In these years, demands for color printing has been increasing in offices, and accordingly color copiers are spreading widely. As one of these color copiers, for example, well known is a 4-drum tandem type color copier. In this type of color copier, toner images of respective colors are formed on 4 tandem photosensitive drums, and toner images of respective colors are transferred and lapped one after another onto a image receiving medium that is transferred via a conveyor belt, and transferred toner images of respective colors are melted and fixed, thereby a color image is output on the image receiving medium.
In more details, toner images of yellow, magenta, cyan, and black are formed on the surface of 4 photosensitive drums. The image receiving medium is electro statically sucked onto the conveyor belt that is rolled over the surface of respective photosensitive drums and run endlessly, and thereby conveyed, and transfer electric fields are formed by transfer means including transferring rollers and transfer brushes and so forth that are arranged to surfaces of the respective photosensitive drums. By these transfer electric fields, toner images of respective colors are piled one after another and transferred onto the image receiving medium, thereby a color image is output onto the image receiving medium.
However, in the prior art, as mentioned above, it was extremely difficult to transfer toner images of 4 colors, i.e., yellow, magenta, cyan and black onto a image receiving medium with their respective transfer positions arranged accurately, accordingly it was hard to output a quality image without color displacement, which has been a problem in the prior art.
Accordingly, the object of the present invention is to provide a belt conveyor that may make a conveyor belt to convey a image receiving medium stably run at a specified position, and an image forming apparatus that is equipped with the belt conveyor, and may remove image displacement output on the image receiving medium that is conveyed via the belt conveyor, and form quality images.
According to the present invention, there is provided a belt conveyor comprising a driving roller; a driven roller arranged roughly in parallel with, and away from the driving roller; a conveyor belt wound around the driving roller and driven roller, to run endlessly by rotation of the driving roller; and a regulation member arranged adjacent to at least one end of the axial direction of the driving roller, to regulate the moving of the conveyor belt in the axial direction of the driving roller; wherein the regulation member has a regulating surface that may slide on and contact to a lower part portion in a range where the conveyor belt contacts the driving roller.
Further, according to the present invention, there is provided an image forming apparatus comprising a driving roller; a driven roller arranged roughly in parallel with, and away from the driving roller; a conveyor belt wound around the driving roller and driven roller, and has a transfer surface to hold an image receiving medium, to run endlessly by rotation of the driving roller; regulation members arranged adjacent to both the ends of the axial direction of the driving roller, to regulate the moving of the conveyor belt in the axial direction of the driving roller; plural image carriers arranged to the conveying surface of the conveyor belt and along the running direction; image forming means for forming a developed image on each of the image carriers; and transfer means for transferring the developed image onto the image receiving medium that is held by the conveying surface and made to go through the plural image carriers; wherein the regulation members have regulating surfaces that may slide on and contact to lower parts in ranges where the conveyor belt contacts the driving roller.